Safety calculator



Oct. 18, 1949. D. P. ANscHlcKs ET' Al. 2,435,181

SAFETY GALCULATOR Filed Dec. 20, 1947 2 Sheets-Sheet l :Q2 l lo Sun non 4515 SBL SEVERITY Rm Numenor DAYS Lun' x zo an 4o SEVERITY RIVES Numan cF ons wm' HOURS lan 200 500 40o S00 60o 700 B00 900 |000 sono :non 4000 suon econ 'moa nooo 9000 FRED UENCY RATES NUMBER oF More. vuucn.: Aumnn'a MILES I 2. 5 4- 5 G 7 8 '9 l0 ZO BO 4 9 50 50 70 8O 90 David Fcflnschlcks Francis @n.wvl'ght @mM/$57114 WVM cH-rvonux/ D. P. ANscHlcKs ET AL 2,485,181

o ct. 18, 1949.

SAFETY CALCULATOR Filed Dec. 20, 1.947

2 Sheets-Sheet 2 16.1.0 eo'mo sona sul nos. 7m.

' SVERITY m5 IDU UD 300 400 50D BCD 100\ 800 90 |000 000 3000 4000 5000 EDUC 10GB H000 B000 ight NVDNTC Dewi YJ. CA nach ick s rowuc @WY hm/ @Zim .MJ/A l Patented Oct. 18, 1949 UNITED STATES PATENT OFFICE vSAFETY CALCULATOR David P. Anschicks, Riverside, .and Francis M. Wright, Berwyn, Ill.

Application December 20, 1947, Serial No. 792,996

17 Claims. 1

The .present invention relates to calculators of theslide rule type and more particularly to calculators for giving the answer, decimal point included, corresponding to a ,given set of data.

It vis an 4object of the present invention-,to provide an improved calculator of the slide rule type .in which the decimal point is located automatically as an incident tothe setting of the slider in accordance with supplied data. It is a related object to .provide a calculator which is particularly well adapted for performing calculations which include large ,multiplying factors such as those used in computing safety rates.

It is another object to provide a sliderule type calculator in which a single table of answer data is utilized ina number .of different calculations, for example, those calculations required for de* termining accident frequency and severity rates.

It -s ya further .object to provide Va calculator `which may be constructed to occupy a volume less than that of the small slide rule While enabling four-place accuracy or greater. It is an allied object to provide a calculator which requires no technical skill in its operation and which may be used by a layman without mathematical exper-V ience with perfect reliability. Since a computation requires but a single setting of the device the correctness of the `answer maybe verified merely by inspection and Without the necessity for checking.

4It is still another objectto provide a calculator which is not only simple and straighforward of construction and attractive in appearance but also one which is easily and cheaply manufactured from readily available materials and using conventional printing arrangements.

Other objects and advantages of the invention will :be apparent from the following detail description taken in connection with the accompanying drawings, in which:

Figure 1 is a general View of a calculator con structed in accordance Awith our invention and wit-h the portion of the face removed to show the tabulation of data on the slider.

Fig. 2 is a fragmentary view ofy a `portieri of the calculator showing the position of the slider in an exemplary computation.

Fig. J3 is a fragmentary View similar to Fig. 2 but showing the relative position of the slider in another exemplary computation.

Fig. 4 is a cross sectional view of the calculator disclosed in Fig. i and showing the laminated construction.

While the invention is susceptible of Various modifications .and alternative constructions and uses, We have shown in the drawings and will herein describe in .detail one embodiment of the invention. It is to be understood, however, that We do not intend to limit the invention by such disclosure, :but .aimto cover all modications and alternative constructions and uses falling within the spirit and scope of the invention as 4expressed inthe appended claims.

In the periodic reporting of injuries and .accidents for statistical purposes, it is necessary for the safety engineer to work out various fre quency rates and severity rates which are determined by the application of standard formulas devised by the American Standards Association. 4Such formulas Irequire the use of data compiled by the reporting .company on the number of injuries or accidents .and the total number of manhours worked. In the case of computing severity rates it 4is necessary to take `into account the number of days .lost together with the arbitrary time charges which `depend upon the extent or seriousness of the disability. In an analogous way .the frequency rates vof motor vehicle accidents may .be determined in terms of the number of miles .travelled by the vehicles in use.

While computing the frequency and severity rates is a relatively simple problem from a mathematical standpoint, nevertheless the standard formulas include factors of up to 1,000,000, the Vpurpose of which is -to avoid expressing the answer as a small decimal. Since the factors in addition to ybeing large are not the same for the various types of calculations, it is found that many errors are made in the reported figures. Such Ierrors have caused safety statistics to be misleading in some instances and in others have required careful investigation and rechecking to insure 'that the gures are accurate.

One of the most important reasons for the difficulties of computation and inaccuracy is the fact that the great majority of industrial plants are not sufficiently large to have a safety engineer trained in this type of statistical work. In the average case the rates are computed by a person having other duties occupying his attention or by a clerk who does not have the necessary background orskill to=deal with the large numbers involved. Even the use of calculating machines is of little help since normal calculating machines are not well -equipped to handle multiplication by a factor of 1,000,000. In general the use of conventional slide rules for thispurpose is out of the question since they .do not have the required accuracy and vsince the placement of the :decimal point is entirely dependent upon the knowledge and skill of the person making the calculation.

Referring now to Fig. 1 of the drawings, the improved calculator indicated at I will be seen to consist of two relatively slidable parts, a body I2 and a slider I4 contained therein. It will be observed that the body I2 is constructed of envelope shape being open at both its upper end I6 and its lower end I8. The ends of the body are cut away as at a, I8a to enable gripping of a i moon-shaped portion of the slider I4. The body I2, as shown in Fig. 4, is preferably of laminated construction including a face I3 and a back I5. The face and Vback are separated by longitudinal spacers I'l at the edge portions of the body in order to provide a central space I9 for easy insertion of the slider.

Arranged on the slider I4 in horizontal rows 2| and vertical rows are figures which together constitute a table 22 of answers to a problem to be performed. The answers are in the form of significant digits, in other words1 the numerals or digits which will appear in the final answer but without location of the decimal point therein, somewhat similar to data obtained from an accurate slide rule of the conventional type. Location of such decimal point required for the final answer is accomplished by other portions of the calculator to be described.

In accordance with one aspect of the invention the face I3 of the calculator includes one or more windows, 24, 26, 28, for viewing a selected portion of the table 22 on the slider. Turning attention now to the window 24 it will be seen that it has at its upper edge a set of reference :i

figures or numerals 32 which are in general vertical alinement with the vertical rows of figures on the table 22. Thus, as the slider I4 is pulled downwardly the gures in the table will be seen to pass the reference figures 32 in alined columns.

In order to determine the proper iposition of the slider I4 with respect to the body I2 for indicating the answer to a calculation, a second row or set of reference gures 34 is used. rIhe row 34 is in the present instance positioned along the left-hand edge of the slider I4 with individual figures 36 in horizontal alinement with the rows 2l in the table 22. In the operation of the calculator the slider I4 is positioned so that a se lected one of the reference figures 36 appears in a window 24a to the left of the window 24. Although a separate window is used for this purpose, it will be apparent that the invention is not so limited but would obviously include embodiments in which a single interconnecting window is used. As a matter of fact, the windows 24, 24a may, in the present arrangement, be considered merely right and left-hand portions of the same window.

The device thus far described may be utilized to obtain the significant digits in the answer to an arithmetic problem, even without location of the decimal point. Thus the first set of reference numerals 32 are preferably used as dividends while the second set of reference figures 34 constitute divisors. The figures in the table are calculated quotients, each of which occupies a position in the table 22 determined by the reference gures as coordinates. This may be made clear by a simple example. Taking the numeral 2 in the set of reference gures 32 and dividing it by, say, the figure 1,050,000 which is the third in the series of reference figures 34, a quotient or answer of 1905 is obtained which is printed at the coordinate point. This quotient as it appears in 4 the table does not, of course, have the decimal point properly located. It does, however, contain the significant digits of the answer to four places of accuracy. Each of the remaining figures in the table 22 is determined in the same manner preferably by the use of a calculating machine.

For the sake of simplicity and ready understanding, only a, portion of the figures on the table 22 and only a portion of the reference figures 36 are shown. The remaining data on the slider may be readily filled in merely by following the pattern which has been set up, until all or a major portion of the slider area contains printed data of the type set forth. As an aid in completing the table 22 it will be noted that the reference figures 36 increase by increments of 25,000. The largest figure in the series, namely the one which would be found at the bottom of the row 34, could, if desired, be 9,975,000, which is one unit short of 10,000,000. The invention is not, however, limited to the particular figures set forth on the slider. The only limitation is that the table give the significant digits of the answer in coordinate location. Thus, the increment between successive figures in the row 34 and the range of such figures may -be entirely determined by the specific requirements of the calculation to be performed. It has been our experience that the values given herein and disclosed in the drawings work out satisfactorily for safety rate calculations.

In using the device thus far described to obtain the significant digits of a quotient, it is merely necessary to draw the slider I4 downwardly until the desired reference figure in the row 34 appears at the edge of the window 24a, in other words, immediately under the word honra Taking the example mentioned above it will be assumed that the figure 1,050,000 is positioned at the upper F edge of the window 24a whereupon the figure 1905 appears immediately under the reference number or dividend 2. That is to say, dividing 2 by 1,050,000 results in a quotient of 1905, expressed in significant digits. In a similar manner the quotient obtained by dividing 3 by the figure 1,050,000 will be found immediately under the figure 3 to be 2857. In a like manner all of the quotients corresponding to the dividends in the set 32 will be found in the window at the coordinate location.

In accordance with the present invention means are provided for not only enabling the significant digits of a quotient to :be immediately read from the calculator, but the decimal point may also be located without any additional operation or effort on the part of the person performing the calculations. In accomplishing this the window 24 and its left-hand portion 24a are preferably covered by a transparent sheet material such as cellulose acetate or similar plastic film. Suitable indicia of the location of the decimal point are then applied to such transparent covering. The decimal indicia in the main portion of the window 24 preferably consist of horizontal rows of decimal points formed of dots of ink as at 38. For a given positioning of the slider, the decimal points 38A fall in successive figures in a horizontal row on the slider. In order to give meaning to such decimal location, it is desirable that the decimal point be simultaneously located in the corresponding reference figure 36 (here a divisor) appearing in the space 24a.

In the case of the reference figures 36, the decimal point is preferably located by means of the border or profile 39 on an opaque mask 4l,

asentar' For exampeathedeeiinarindiciunrfinthervwindow" 24a correspondingxto =f the decimal indicia 38: consista-cf .then short. verticalolinealz'.. It; .will tbe."4 noted that .the-:lirre=. 4:2,is .fan tof. the right; `permitting the figures in the;rcw.'34 to be-viewed. in full width... Thusthediyisorsf appearing: adacent the line `l2 willieaclr befseven.y decimal placesain length. Each." thousands place. is ;denoted. by a comma 48'.

In most practical calculations t'will be 'desirablefto use,:divisors:which.are considerably smaller than seven` decimalplaces .in lengthi... AFor: eit-I amplev instead of. using a divisor of l.;050,000, as im the samplecalculation above; it may be desired to-employ a divisor havingcone-less decimalplace, to. wit,-, 105,000', while` still enabling vdirect decimaly reading of the quotient. This is accomplished in. thefpresentv invention by yproviding means. for shortening the. divisor by one decimal place, here. the.1 short vertical; line'. 40 which` forms a portion of the: contour of themask 40, and by providing. a correspondingly displaced set of decimal indicia.v 44... `As disclosedinlig. 1 thesefare locateddownwardly and onevdecimalfplace tothe right of the decimal. indicia. 38. It. will also be noted. that the line 4.6 -is downwardly and to the left of the line 42. Ipreviously referred to. The commas M3l are progressively shifted to. the left to correspond |with the` change in'decimal location. In a like manner a third.y horizontal. row 50- of decimal indicia may befused together with four, five, and even additional.. levels of displaced indicia as required in. the solution of. the practical problem for whichy the calculator is to be used. Four decimal levels enable the `use of divisors as small as.1,000 such range being satisfactory for all normal safety calculations.

The: mask. 40K hasbeen used. inpreference to employinga :diagonal series of. decimal points` at 39 since it hides the, unused right-hand. portion of.- the reference. figure or divisor in.. the row 34.. This enablesthe" operator to locate a gurefof reducedr width. and magnitude iny thefwindow 24a. without anyv distraction whatsoever caused: by the unused.y decimal places. It will benoted. that both. the; decimal indicia as formed by thea edge:

39. and: by.y the decimal) points. 38,;40, 48 appear.

india-gonal' rows. ThisV is.` one of theadistinctivefeatures. off. the present calculator: and is; indica-- tive .for the factA that as the number of: places in the?divisordecreases,v the number of places in the quotient correspondingly increases. Thedecmal.l points 38p 4.4; 81y thusextend downwardlyl :to the: right .while thexdecimal .indicia 39 in theportion 24m of the'windcwv extend downwardly torthe left. In@ each case: the .arrangement can be'referred to as. stepped Having understood the physical constructionv of, thecalculator particularly' as regards. the. windcw24; and thedecimal indicia associated therewith, it will be apparent to. one skilled in the art that the calculator. is .adapted toperform simplek problems of.. calculation. which maybe encountered in many fields offendeavor. Thecalculator has;` however, been.l particularlyy satisfactory for solvingthe frequency rate formula which is to be; found inthecodeof. the American Standards As-A sociation. andwhichis standard throughout the. industry' as" ayard'stick. in..determining4 how fre-v quently injuries occur. rI-hisv formulav is; as. follows.:

Ituthree inuries. occurred during-al periodI of.

=Frequency rate 1004000 ,.fmair-fhuurss: thez: frequency rate' V'may be readily ascertained.. The. setting: of the. slider `I 4i oor-.rfispnnding such calculation is. shown at 6.8.'

so that k.iilief number: 1'0I1g000i` appears. under the word:hoursf atthe letti-:hand sidefof the window 24".. Reading: .directly under' 3? which correspond'slto thanumber of injuriesv (and: is .so.` entitledgnonexfindsi than.lglure;v 30:00.'. This is the ligure. which i's` employed? for statistical purposes. andisigniesthatithe frequency rate is 30.injuries.

. noted thatth'efopaque mask' 52 at the left-hand portion'of thek window` 2liy and lwhich corresponds to-"che--maslr` '.40 i'sl suliastantially unchanged.

Opaquamasks-*54v running from theI top4 to the bottomof the windowZGf are'used to enable the decimall point tov extend* to thek left and into the regi'onroccupie'd Vby the" adjacent row ofv figures. At'theupperport'ion ofeachfof the masks'54 are decimal points -58 and additionall ciphers4 56 are used -toflliin the space between such decimal; .l point Wfandi'the portion 60; of the Window which' isl to be*occupiedibyv the yfigure constituting theI quotient, Decimal' -indicia G2" formed of printed" dotsorr the transparent'windowA material may be used-'inthe-samemanner as disclosed in-connectionfwithftheiwindow 24.

Theusevo`the'-windows 26, 28" inn determining severity rates- Will" rbe 'made'r clear by considerin g" the formulawhich is-'used asI a standard iny such calculations;v This formula-appears as follows:

(Number ofdayslost-{ftime charges) .l,000 ;'Dotalmanfhounstwcrked Severity rate Suppose that inca .period of-..100,00'0 man-hours thereehadlbeen accidents producing totallost time off 20d-.days and.l` further that. one of the accidents involved?thalcssaotxathumb.. Sincef theloss of a thumb resultslin a` certain: amount of permanent disability, such loss increases the rate of the industrial plant.. -A sealeof' time chargeshas been setoupabyf, the American: vStandards Associationy.

aznumberf-offfwhiclr. are'listed at. 64' in Fig. 1. It

willi` be noted. at 6E intthis.: scale. that.. the lossof a.

thumbxis countedfas aa penalty of. 600. days-, andv thusiit .-is'necessary.- to add thev two figures to produce amaggregatezof; 80.0'days lost.

:Torperfornathecalculation,l window 28 isused, thef slider I4. being: positioned so. that the reference: figue-100,000; appears.: in. the left-hand portion..=28f1.a.oftlriewindow under hours Such positioning; ofid thefslider is shown at Fig. 3- of the drawings. :The severity rate,l indicated at 10 in.

Fig.a3, isthus 8.000.

Itwill be apparent'. that if` 80 man-daysy had been lost inthisperiod. rather than 8.00 as in the. foregoing example, the. severity rate would4 then be neadunderf the figure 80 nwindow 2G as.800.

Similarly; if. only 8i-days-.were lost the rate is read.

as. .08000. `Thisserves toillustrate: the Wide range of. rate: which: may be `directly read onthe present calculator.v

As a further example oi the manner in which the calculator may be employed to obtain a composite severity rate, let it be assumed that the number of days lost in 100,000 man-hours of work was 888. In order to obtain the severity rate it will be necessary to split such iigure up into three parts, 800, 80 and 8 man-days. The respective severity rates of 8.000, .8000 and .08000 (as found above) are then merely added together to produce a resultant severity rate of 8.8800. The latter step is an extremely simple one and not appreciably subject to error.

The calculator is also ideally suited to obtain the frequency rate of motor vehicle accidents. In such case the row of reference figures above the window, in this case window 30, corresponds to the number of motor vehicle accidents while the reference figure at the left-hand portion of the window is read in terms of miles rather than hours. The frequency rate is obtained from the following standard formula:

Number of accidents l00,000 Miles travelled The rate may be read directly by setting the appropriate number of miles in the space provided and reading the rate under the appropriate number of accidents. The rate is in a coordinate position just as in the examples previously discussed.

It will be apparent to one skilled in the art that the invention disclosed herein is not limited to the specific form of safety calculator disclosed but obviously includes many other equivalent calculators which may be constructed utilizing the teachings disclosed herein. Calculators of this general type are of considerable utility in a wide variety of elds. In adapting the calculator for other specific calculations, it is merely necessary that rows of reference iigures 32, 34 be set up covering the probable range of data to be supplied. It is further necessary that the `coordi nate point on the table 22 include the answer which should result from the use of such data, such answer being preferably calculated in the first instance by using mechanical or other type of calculator. Then the decimal indicia are added to the window or aperture through which the table 22 and the row 34 of reference figures are viewed. Such indicia are so located that the decimal point is properly placed in the answer automatically as an incident to properly locating the decimal point in the reference figure in the row 34, all as described in the examples given above.

While the invention has been described in connection with the preferred embodiment including a series of windows, it will be appreciated by one skilled in the art that the invention is not so limited but includes arrangements in which portions of the face I3 shown as opaque are made transparent. The present construction has the advantage that portions of the table 22 not of interest in a particular calculator are, for the most part, hidden from view thus reducing possible distraction and the chances of error to a minimum. Nor is the invention limited to calculators of generally rectangular shape but obviously includes constructions in which the relatively sliding surfaces are cylindrical or radially pivoted, completely analogously to the cylindrical and circular type of slide rules.

While both the construction and operation of the calculator will be apparent from the foregoing, it should be stated, for purposes of completeness, that the showing in Fig. 1 is simplified to the extent that certain figures in the table 22,

=Frequency rate 8 normally viewable through the windows 24, 26, 28, 30, have been omitted. In this way the positioning of the decimal points 38, 44, 50 on the transparent Window material can be more readily seen.

We claim as our invention:

1. In a calculator the combination comprising a body member having a face portion, a slider insertable under said face portion, said slider having a table of answers thereon consisting of figures arranged in horizontal and vertical rows, a vertical row of reference figures alongside said table, a plurality of transparent windows on said face portion for viewing a selected horizontal portion of said table, a set of stepped decimal indicia on said face portion and cooperating with the reference figures in said vertical row so that upon sliding adjustment of said slider a selected one .of said decimal indicia may be positioned relative to a selected one of said reference figures to properly locate the decimal point in the latter, a horizontal row of reference figures adjacent each of said windows respectively and arranged in respective alinement with the vertical rows of figures in said table, said windows having a second set of decimal indicia imprinted thereon in stepped relation and so related to said first decimal indicia that the answer corresponding to a selected pair of coordinate reference figures may be read oli directly and with the decimal point automatically properly located therein.

2. In a calcrdator the combination comprising ilrst and second relatively slidable members, said nrst member having a table of answers to a mathematical problem and having a vertical row of reference figures alined with the respective answers corresponding thereto, said second member having a plurality of windows therein each having a horizontal row of reference gures positioned adjacent the edge thereof and alined with the respective answers corresponding thereto, individual reference figures in the row associated with each of said windows differing only from corresponding reference figures in the remaining rows in the location of the decimal point, and means on said second member overlying at least a part of the data on said rst member for locating the decimal point therein so that the correct answer including the decimal point may be read from said table at the coordinate corresponding to a selected pair of reference figures.

3. In a calculator the combination comprising first and second relatively slidable members, said first member having a table of answers to a mathematical problem and having a vertical row of reference figures alined with the respective answers corresponding thereto, said second member having transparent portions and having vertically spaced horizontal rows of reference figures alined with the respective answers corresponding thereto adjacent said transparent portions, individual gures in each of the latter mentioned rows differing only from corresponding figures in the other rows in the location of the decimal point, and means on the transparent portions of said second member overlying at least the answers in said table for locating the decimal point so that the correct answer including the decimal point may be read from said table at the coordinate corresponding to a selected pair of reference figures.

4. In a calculator the combination comprising first and second relatively slidable members, said rst member having a table of answers to a mathematical problem printed thereon and having a vertical row of reference iigures alined with the respective answers corresponding thereto, said second 1rrrember having a plurality y'of `windows -of transparent material therein each y'having a hori- .zontalflrowfof reierenceiigures positioned adjacent itheedgethereof .andfa'lined with'the respective `answers corresponding thereto, `individual 4reference figures in the row associated with each :of :said windows dir ering only trom fcorrespond- Ying reference :glures'in the remaining :rows `'in ythe l'oca'tionlof theidecimal point, means onsaid secvond .member Tor selecting one of the reference Jigures in said vertical Arowupon relative slidable positioning 'of said members, vand decimal points imprinted on 'the windows `oisaid second `member andxoverlyling the table 'of :answers 'on said `-irst ymember for automatically locating one `oi said decimal points :in 'the answer which lies fat the 'coordinate corresponding ito` :a selected Vpair yof .reference figures.

f5.. 4In a :calculator the .combination compri-singv ,asairst tmember, -a thin Isc-cond: Ymember overlying said .iirst member .and relatively slidable with re- :sncctttheretd said first nieniber fhavingfa tablelof answers to .acmathematioa'l problem expressed in the form of significant ilgures and having-ayern 'tical row :oil erenoeiigures 1in .alinement with .respective `answers `corresponding thereto, said :second member having :a .plurality :of windows fthere'in, .each .having .ahorizontal .row of .referonce .figures spacedza'long .the edge thereof, .individnal=-reier-ence gures inthe Arow:associated with y@sach .of .-saidiwindows .having the same signiiicant digits :and `difiering from .corresponding 'reference fin the remaining horizontal. rows only in fthe location @of the decimal point, means on said second member'for :selecting one of Vthe .refer ence iigures in said vertical row. upon relative positioningof said membersand meansincluding masks having fdecirnal indicia 'thereon :associated with at least certain ones '.of said windowsand .superimposed on theidata on Isaid first member, `said i.indicia ybeingso vpositioned as .to-properly -locate -the .decimal .point in the answer corespondto a selected ,pair ofgeferencegures.

6. In a ycalculator the combination comprising first and secondk members in -surface-to-'surface sliding engagement, said lsecondmember lpresenting a 'horizontal-ledge portion cooperating with the surface oi said .rst.member and having :a horizontal .row of reference .figures thereon, :said rst member havinga Atablezof figures 'thereon varranged both `in horizontal .rows parallel to said horizontal edge portion and 1in lvertical rows in alinement with individual ones -of '.thefigures .on said edge portion,.saidliirst member also `having a vertical row of reference figures Vadjacent said table and in horizonta-lalinementltherewith, said second .member vhaving-a series fof fsteppedrmasks extending from f-said fed-ge portion and overlying the` vertical rows .in said table and having a stepped mask overlying :said vertical row of reference figures, said latter named mask 'being stepped in a direction opposite to said series of masks said guresbeing :so related that acoordin'ate figure in' said 'table selected 'by relatively positioning said members is the quotient Aof `a problem yin which corresponding lreierence gures in the horizontal Aand vertical rows constitute :the dividend and divisor.

7. In a .calculator the combination comprising a nrst member, a second 'member `overlying said iirst member vand lin surface-'to-sur-face sliding engagement .therewith,..said second member presenting an edge portion cooperating ywith the surface :of said first .member :and having afhorizontal row-:of reference igures spaced .therealong said Afirst*member 'having a itable of "figures thereon arranged 'both in horizontal rows parallel tosa'id edge 'and in vertical 'rows which are alined 'with individual `ones vof said'gures on said `edge portion, said first memberalso having a vertical :row of vreference gures adjacent said `table and in horizontal alinement therewith, a mask adjacent :to said 'edge portion and voverlying 'said table, said mask including a series of diagonally 'arranged decimal 'indicia for each of 'the vertical rows rol" gureson said rfirst member, said *gures being so related 'that 'a given coordinate gure :in said table includes the signicantgures of an answer to a problem in which the corresponding reference gures yin the horizontal and vertical rows `constitute the :supplied data, said decimal indicia Ibeing so :arranged that when said mem-- bers 4are relatively 'positioned to properly place the decimal :point in a selected reference figure in lthe `vertical row, the decimal is also properly placed in the'answer.

8. In a calculator ythe lcombination comprising arst member, a second 'member overlying vsaid -rst member and in surface-to-surface sliding engagement therewith, said second lmember presentingan edge portion cooperatingwith thesurface of said iirst member and having a horizontal row'fof reference iigures spaced 'therealong said iirst member having Aa table of figures thereon arranged both inhorizontal rows parallel to said edge and in vertical rows -which are alined Awith individual ones of said iigures on lsaid edge 'portion, said vrst member'also having va vertical `row vof reference figures 4adjacent said. table and. in 1horizontal alinement therewith, a ymask adjacent to said edge lportion vand'overlying said tablegsaid Vmask including a lseries or stepped decimal iinfdicia for each of the vertical rows of gures-on said :first member, said -gures lbeing so related .that 'a -given 'coordinate figure in vsaid. table 4includes the .significant-gures of the quotient fof af problem in which the corresponding reference .guresinthe horizontal and vertical rows constitute Athe supplied dividend and divisor, said decimal points being .so .stepped that when .said members are 4relatively positioned to .properly place the decimal `point in a .selected reference figure in the vertical row, the decimal is Aalso properly placed in the-quotient.

9. .In a calculator the combination lcomprising a, first member, a .second member overlying said rst'member and in surface-to-surface sliding engagement therewith, said second member Apresenting an edge portion to said first member and having a row of reference figures spaced therealong, said rst member having a table of gures thereon parallel to said edge portion and in vertical alinement with individual ones of the reference figures on said edge portion, said rst member also having a reference figure thereon adjacent said table, said second member having a mask joined to said edge portion and overlying said rst member, said mask including rows of diagonally araranged decimal points, one row -ior each 0i" said reference gures, all of said 'figures being so related that a given gure in said table includes the significant digits of the answer to a problem in which the corresponding reference figures constitute the supplied data, said decimal points :are so 'arranged on said mask that when said members are relatively moved to properly place the decimal point in the reference figure on said first member, the ldecimal point is also properly placed in the answer.

10. In .a 'calculator `the -combination comprising a iirst member, a second member overlying said rst member and in surface-to-surface sliding engagement therewith, said second member presenting an edge portion to said first member and having a row of dividends spaced therealong, said rst member having a row of quotients thereon parallel to said edge portion and in alinement with individual ones of the dividends on said edge portion, said rst member also having a divisor adjacent said table, a mask stationarily mounted with respect to said edge portion and overlying said table, said mask including rows of diagonally arranged decimal points thereon for the iigures on said iirst member, said decimal points being so arranged that when said members are relatively moved to properly place the decimal point in the divisor, the decimal points are also properly placed in each of said quotients.

11. In a calculator the combination comprising first and second members in surface-to-surface sliding engagement, said second member including a transparent mask portion having a horizontal row of dividends spaced therealong, said iirst member having a table of quotients in vertical alinement with individual ones of the divif dends on said edge portion, said iirst member also having a vertical row of divisors adjacent said table, said mask having rows of diagonally arranged decimal points indicated thereon, one

row for the row of dividends and one row for each of the rows of quotients, said decimal points being so arranged that when said members are relatively moved to properly place the decimal points in a selected one of the dividends on said first member, the decimal point is also properly placed in each of the corresponding quotients.

12. In a calculator the combination comprising a iirst member having a divisor and a row of quotients alined therewith, a second member slidable on said iirst member and having a window of transparent material for observing said divisor and said quotients, a set of dividends arranged adjacent said window and alined with corresponding quotients on said iirst member, said window having diagonal rows of decimal indicia arranged to overlie said divisor and said quotients, said decimal indicia being so arranged that relative movement of said members to position a decimal point in a desired position in said divisor automatically causes decimal points to be properly positioned in all of the quotients alined therewith so that a quotient corresponding to given dividend and including the decimal point may be read off directly.

13. In a calculator the combination comprising a first sheet member having a row of divisors and a table of quotients adjacent thereto, a second sheet member slidable on said iirst member and having means including a window of transpar- .l

ent material for observing said divisors and said table of quotients, a row of dividends arranged along the edge of said window and alined with corresponding quotients on said rst member, a stepped opaque mask on said second member for overlying the row of divisors on said rst member, said window having a diagonal row of decimal indicia adjacent each of said dividends and arranged to overlie said table of quotients, said decimal indicia being so arranged that relative movement of said members to position said mask in a predetermined position in a selected divisor automatically causes decimal points to be properly positioned in all of the quotients in alinement therewith so that a quotient corresponding to a given dividend and complete with decimal point may be read oi directly.

14. In a calculator the combination `comprising a body member of envelope shape and open at at least one of its ends, a slider insertable within said body member, said slider having a table of figures printed in rows thereon, said body member having a plurality of windows of transparent material, any one of which may be selected for viewing said table upon withdrawing said slider an appropriate amount, each of said windows having a set of reference iigures respectively alined with the rows of figures of said table, each oi said windows also having a diagonal row of decimal indicia thereon for locating the decimal point in the vertical reference figures in said table when a selected portion of the latter is located under a Selected window and additional diagonal rows of decimal indicia overlying the visible answer iigures on said table so that the visible answer figures in said table corresponding to a given one of the reference iigures may be read off directly with the decimal point properly placed.

15. In a calculator of the slide rule type the combination comprising a body member, a slider in said body member having a table of answers printed thereon, said body member having a window therein for viewing a selected portion of said table, indicia on said body and slider settable in accordance with supplied data for indicating the positioning oi said slider required for eX- posing the portion of said table in which the answer corresponding to said supplied data is to be found, said window having means including a stepped border for cutting 01T the digits of lesser signiiicance in the answers in said table and for locating the decimal points therein to enable direct reading of the answer.

16. In a calculator of the slide rule type the combination comprising a body member, a slider in said body member having a table of answers printed in vertical rows thereon, said body member having a window therein for viewing a selected portion of said table, indicia on said body and slider settable in accordance with supplied data for indicating the positioning of said slider required for exposing the portion of said table in which the answer corresponding to the supplied data is to be found, said window having stepped masks of opaque material cooperating with at least a portion of said vertical rows for cutting off the digits of lesser signiiicance in the answers in said table, said masks being overprinted with ciphers for enabling the decimal point for one row to overlap the adjacent row.

17. In a calculator the combination comprising a body member having a face portion, a slider insertable under said face portion, said slider having a table of answers thereon consisting of figures arranged in horizontal and vertical rows, a vertical row of reference iigures alongside said table, said face portion having a plurality of windows for viewing a selected horizontal portion eof said table and a corresponding portion of said vertical row of references iigures, a iirst set of stepped decimal indicia so located on said face portion with reference to said windows as to cooperate with the vertical row of reference figures so that upon sliding adjustment of said slider a selected one of said decimal indicia may be positioned relative to a selected one of said reference ligures to properly locate the decimal point in the latter, a horizontal row of reference figures adja- 75 cent said windows and arranged in respective 2,485,181 K v 13 14 alinement with the vertical rows of gures in said REFERENCES CITED table, said Windows having a. second set of stepped decimal indicia so related to said rst set of decimal indicia that the answer corresponding The following references are of record in the file of this patent:

to a selected pair of coordinate reference iigures 5 UNITED STATES PATENTS may be read off directly and with a decimal point Number Name Date automatically properly located therein. 856,573 Draper June 11, 1907 1,336,900 GalloWa A r. 13, 1920 DAVID P. ANSCHICKS. 1,491,800 y p H d r A r. 29, 1924 FRANCIS M. WRIGHT. 1o en e son p 

